title: Stability of vancomycin-resistant enterococcal genotypes isolated from long-term-colonized patients.
abstract: Genotypic variation and stability of isolates of vancomycin-resistant enterococci (VRE) were studied to determine genetic diversity and whether strain definition based on pulsed-field gel electrophoresis (PFGE) is applicable to an endemic setting. Twenty-two PFGE types were identified among 455 VRE isolates. One-on-one comparisons of 10 vanA Enterococcus faecium strain types all yielded > 10 band differences. Variations among vanA and vanB E. faecium isolates from individual long-term-colonized (4-160 days) patients yielded < 3 band differences for > 85% of comparisons. Comparison of all strains without grouping by vancomycin resistance types yielded two peaks of band differences: one with < 3 and one with > 10 band differences. These data show that VRE isolates were genetically closely related or very different; demonstrate that within individual patients, VRE isolates show little genetic variation; and provide empirical evidence that PFGE can be used to study the epidemiology of VRE endemicity.
authors.affiliation: Department of Internal Medicine, Cook County Hospital, Rush Medical College, Chicago, Illinois, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Bonten
authors.forename: M K
authors.initials: MK
authors.lastname: Hayden
authors.forename: C
authors.initials: C
authors.lastname: Nathan
authors.forename: T W
authors.initials: TW
authors.lastname: Rice
authors.forename: R A
authors.initials: RA
authors.lastname: Weinstein
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D016983:Enterococcus / Q000187:drug effects / Q000235:genetics*; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics; D014644:Genetic Variation; D016680:Genome, Bacterial; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D011159:Population Surveillance; D015995:Prevalence; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D014640:Vancomycin